EFFECTS OF METHYLISOCYANATE ON SOIL MICROFLORA AND THE BIOCHEMICAL-ACTIVITY OF SOILS

Methylisocyanate at 500, 1000 and 2 500 mug ml-1 h-1 markedly affected the fungal propagules in treated soils. Immediately after exposure to gas, both bacteria and actinomycetes were appreciably reduced, although by the seventh day, their populations had gradually increased. Increased soil respiration was evident at 500 mug ml-1 of methylisocyanate, whereas, inhibition of respiration occurred at 1000 and 2 500 mug ml-1 h-1. Methylisocyanate adversely affected soil nitrification; inhibition increased with increasing concentration. Up to 2 500 mug ml-1 h-1, it stimulated ammonification, but the NH4-N level gradually declined with increased incubation.